Estimating the phase of a signal is an important function that finds application in a number of areas, such as in communication and signal processing. One such application in which phase estimation accuracy is important is in experiments for detecting gravity waves, whereby laser signals received from one or more spacecrafts convey information regarding small changes in the relative distances between the spacecrafts. Such changes in the relative distances may indicate gravity waves. For such an application, a locally generated reference laser signal “beats” with the received laser signal to provide a signal comprising a tone having a frequency equal to the difference of the frequencies of the received and locally generated laser signals. This beat tone may be referred to as a heterodyne interference frequency, and the beat signal may be referred to as a heterodyne interference signal. Accurately measuring the phase of the heterodyne interference signal provides information regarding the change in distance between the spacecraft.